Rock is gained from the earth for crushing by exploding or excavating. Rock can also be natural and gravel or construction waste. Mobile crushers and stationary crushing applications are used in crushing. An excavator or wheeled loader loads the material to be crushed into the crusher's feed hopper from where the material to be crushed may fall in a jaw of a crusher or a feeder moves the rock material towards the crusher.
Intermediate and fine crushing is continued generally with gyratory and cone crushers after a jaw crusher. Then it is an object to produce for example gravel or fine sand. Gyratory and cone crushers break all rock materials but not always recycled materials. Big primary cone crushers are used in mines in the primary crushing phase and other mining and quarrying applications which are requiring large capacity. Small rock crushing plants can yield 100 to 300 tons of crushed rock per hour, middle sized 300 to 600 and large plants 600 to 1 000 tons per hour. The largest rock crushing plants may produce even more than 2 000 tons crushed rock per hour. For instance 25 000 to 50 000 tons of crushed rock are required for making an asphalt road which is one kilometer long and ten meter wide.
Gyratory and cone crushers are adjusted for different production requirements by changing the profile of the crushing chamber, the amount of the eccentric movement, i.e. the stroke, the rotation speed of the crushing cone and the setting of the crusher.
Surface height of the material to be crushed is influencing product distribution and power intake of the crusher. When the surface height in the feed hopper is high, pressure of the material downwards in direction of the crushing chamber is increasing. The high pressure is changing function of the crushing chamber and causes increasing wear of wear parts of the crusher. Additionally the crusher is consuming more energy and the end product distribution is changing. The power increase is also increasing the finer end product 0-4 mm which is giving a lesser sales price than the objected coarser end product.
The crushing chamber of current crushers cannot be adjusted during crushing. The adjusting takes place by changing the wear parts or part of the wear parts of the crusher. The gyratory/cone crusher has to be stopped and partly disassembled for this purpose.
A relieving stationary shelf has been used in some crushers in the upper portion of the crushing chamber, the purpose of this has been to prevent crushing of stones in the upper portion of the jaw.
The fine material produced by the crusher and the power required by the crusher cannot be adjusted satisfactorily by the prior art technology.
JP 2002018297 A describes a cone crusher by which mineral material is crushed by moving the moving cone in relation to a stationary crushing chamber. The crusher is equipped with a feed hopper by which the material to be crushed is directed through a feed opening to the crushing chamber.
EP 0628348 B1 describes an impact based crusher in which the material to be crushed is shot by a rotor which is rotating around a vertical axis in side direction against a crush wall. A storage silo is connected in front of the crusher wherefrom the material flows through a feed opening to the crushing chamber. It is tried to avoid proceeding of superfluous air in the crusher and to decrease generation of dust.
An object of the invention is to adjust a crusher during crushing. A second object of the invention is to control the power intake of a crusher. A further object of the invention is to adjust the product distribution and particularly the amount of the fine material produced by a crusher.